Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human Biology > Module 5: The Muscular System: Histology and Physiology > Flashcards

Module 5: The Muscular System: Histology and Physiology Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What are the three major tasks of the muscular system?

A

Movement, posture, and heat production.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name some examples of how muscles impact movement.

A

Muscles move the skeleton, tongue, and diaphragm. They push food through the digestive system, urine from the urinary bladder, and blood through the heart and blood vessels. They constrict and dilate the pupils of the eyes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the three types of muscle tissue?

A

Skeletal, cardiac, and smooth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Striated

A

A distinct, orderly striped pattern of muscular tissue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Voluntary muscles

A

Muscles you can control consciously, including all the muscles that move the bone, tongue, and diaphragm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name some characteristics of skeletal muscle.

A

Striated, a voluntary muscle, and long, thin, multinucleated cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Involuntary muscles

A

Muscles you cannot exercise control over.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name some characteristics of cardiac muscle.

A

It is found only in the heart, striated, and involuntary.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference in the striation of skeletal and cardiac muscle?

A

They are both striated, but skeletal muscle is multinucleated and cardiac muscle is not.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name some characteristics of smooth muscle.

A

Involuntary, nonstriated, the cells are small with one nucleus, and it enables the internal organs to do their job.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the four major functional characteristics of muscle tissue?

A

Contractility, excitability, extensibility, and elasticity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Contractility

A

The ability to contract forcefully.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Excitability

A

The characteristic of cells that can produce action potential signals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Action potential

A

The cellular response to a stimulation from the nervous system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is action potential essential to muscle cells?

A

Action potential signals the cells to contract, and action potentials produced by neurons also allow the nervous system to control skeletal muscles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Extensibility

A

The ability to passively stretch out.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Elasticity

A

The fact that when the muscles are extended, they tend to recoil back to a shorter length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Tendon

A

A strap of dense regular connective tissue that connects muscle to bone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where are the actual muscle cells found?

A

The belly of the muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Fascicles

A

Bundles of cells which divide up the muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Muscle fiber

A

A muscle cell. They are long and thin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Endomysium

A

A thin collagen layer surrounding every muscle cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Perimysium

A

A collagen layer that wraps around each fascicle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Epimysium

A

The collagen layer that binds all the fascicles together and what differentiates one muscle from another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is another term for the epimysium, and why is it not commonly used when speaking about muscle?

A

Fascia. It refers to sheets of tissue that lie underneath the skin in a much broader sense. Epimysium specifically describes a muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How are muscles secured to bone?

A

The collagen fibers that make up the endomysium extend past the end of the muscle belly and form the dense regular connective tissue of the tendon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does a tendon connect to a bone?

A

Both bone and tendons have collagen. The collagen in the tendon continues into the bone and becomes a part of the bone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why are there so many blood vessels in muscle?

A

Muscles are high users of nutrients and oxygen, so they need a lot of blood vessels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why are nerves essential to muscle activity?

A

A skeletal muscle will not contract without nerves to stimulate it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where are the nuclei of skeletal muscle fibers found?

A

Just under the sarcolemma.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Sarcolemma

A

The plasma membrane of muscle fiber.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Sarco

A

Means “flesh” or “meat.”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Sarcoplasmic reticulum

A

The endoplasmic reticulum of a muscle fiber.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

T-tubules

A

Tiny tubes in the sarcolemma that extend into the sarcoplasmic reticulum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the purpose of T-tubules?

A

They allow the action potential to reach the sarcoplasmic reticulum in order to stimulate muscle movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What do myofibrils look like?

A

Thread-like structures that are only a few micrometers in diameter. They are long and extend from one end of the cell to the other, structured in repeating units that cause the striations of muscular tissue.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What two basic types of filament does each unit of myofibril contain?

A

Actin myofilaments and myosin myofilaments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Myofibril

A

The contractile units of skeletal muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Why do the strands of muscle fiber have striations?

A

The striations are caused by the fact that myofibrils are composed or repeating units called sarcomeres.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Sarcomere

A

The repeating unit of a myofibril.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What two proteins make up a sarcomere?

A

Myosin and actin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Prefix “myo”

A

Muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Prefix “sin”

A

Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Is the myosin myofilament or the actin myofilament thicker?

A

The myosin myofilament.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Cross bridge

A

The basis of muscle contraction. The combination of a myosin head with the active site of an actin myofilament.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How does a muscle fiber contract?

A

The head of the myosin grasps the actin at its active site and pulls on it, shortening the sarcomere. All the sarcomeres in the muscle fiber do this at the same time, so the entire muscle fiber contracts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Why do the sarcomeres show striation?

A

Myosin is thicker than actin, so it appears darker under a microscope.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

A bands

A

The thick, dark stripes of myosin in a sarcomere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

I bands

A

The portions of the sarcomere with action myofilaments and no myosin myofilaments. Shows up as thin and light on the microscope.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the purpose of a Z disk?

A

It serves to anchor the actin myofilaments and mark the boundaries of the sarcomere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

The H zone

A

The area within the A band where no actin is present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What defines the A band?

A

The myosin myofilament. The A band is the exact length of the myosin myofilaments.

53
Q

Why does a muscle bulge out when flexed?

A

The whole muscle is shorter and thicker because the actin and myosin are more overlapped.

54
Q

What parts of a sarcomere change length when contracted?

A

The length of the entire sarcomere, the H zone, and the I bands all become shorter.

55
Q

What parts of a sarcomere do NOT change length when contracted?

A

The length of the actin myofilaments, the myosin myofilaments, and the A band.

56
Q

Summarize the first step of muscle contraction.

A

At rest, before contraction, the active sites on the actin myofilament are not exposed. Thus, the heads of the myosin myofilament are primed and ready, but they can’t bind actin. The contraction can’t happen.

57
Q

Summarize the second step of muscle contraction.

A

To start a contraction, Ca2+ bind to the troponin, causing tropomyosin to move away from the actin myofilament. This exposes the active sites to which the myosin heads can bind. Phosphate is ejected when the myosin heads bind to the active sites.

58
Q

Summarize the third step of muscle contraction.

A

Power stroke: The myosin heads then bend, pulling the actin myofilament toward the center of the sarcomere. This causes the ADP to be ejected.

59
Q

Summarize the fourth step of muscle contraction.

A

ATP molecules bind to the myosin heads, causing them to break their bond with actin’s active sites. As a result of the power stroke from the heads in step 3, the actin myofilament has moved.

60
Q

Summarize the fifth step of muscle contraction.

A

Return stroke: ATP molecules break down into ADP and P, which stay bound to the myosin heads. This releases energy, and the myosin heads are now powered up like a set mousetrap, ready to start the process all over again.

61
Q

Motor neurons

A

Cells specifically designed to carry action potentials from the brain and spinal cord to the skeletal muscles at a high rate of speed.

62
Q

Neuron

A

The functional unit of the nervous system; a nerve cell.

63
Q

Axon

A

The long process of a neuron that carries signals away from the main cell body.

64
Q

Neuromuscular junction

A

The connection of an axon with a muscle fiber.

65
Q

Synaptic cleft

A

The tiny gap between the end of the axon and the muscle fiber in a neuromuscular junction.

66
Q

Synapse

A

The interface between a neuron and another cell.

67
Q

Presynaptic terminal

A

The very end of a neuron.

68
Q

Postsynaptic membrane

A

The membrane of the muscle fiber in the synaptic cleft.

69
Q

Vesicle

A

A sac-like organelle that holds substances for the cell.

70
Q

What is the purpose of synaptic vesicles?

A

They stimulate muscle fibers and store ACh. (acetylcholine)

71
Q

Neurotransmitter

A

A chemical released by a neuron, which diffuses across the synaptic cleft, enabling the neuron to communicate with another cell.

72
Q

What does ACh (acetylcholine) do?

A

When it is released from the neuron’s presynaptic terminal, it binds to the postsynaptic membrane of a muscle fiber and initiates a series of signals that cause the muscle fiber to contract.

73
Q

Describe the basic process that occurs before a muscle contracts.

A

The motor neuron release ACh into the synaptic cleft. The ACh binds to the muscle fiber, forms a signal, and that signal starts other processes, which will signal the muscle fiber to contract.

74
Q

Acetylcholinesterase (ACh-ase)

A

An enzyme that inactivates ACh so the muscle can relax.

75
Q

What does “ase” on the end of a chemical’s name usually mean?

A

It is an enzyme that acts on a chemical.

76
Q

How do the first and second action potentials differ from each other?

A

The first action potential travels along the axon of the neuron, and the muscle action potential (the second one) travels through the sarcoplasm (cell membrane).

77
Q

T-tubule

A

The pits in the sarcolemma that lead to the sarcoplasmic reticulum.

78
Q

Why are Ca2+ ions important in muscle contraction?

A

They attach to the troponin in the actin myofilament and cause tropomyosin to move and expose active sites for the myosin heads to bind. These ions allow cross bridges to form.

79
Q

Where are Ca2+ ions stored?

A

The sarcoplasmic reticulum.

80
Q

How do Ca2+ ions enter the sarcoplasmic reticulum?

A

The membrane of the SR uses active transport and expends ATP to bring the ions in because the concentration of Ca2+ inside the SR is greater than outside.

81
Q

What causes the Ca2+ of the sarcoplasmic reticulum to be released?

A

The movement of muscle action potential from the sarcolemma down the T-tubule into the sarcoplasmic reticulum.

82
Q

Where does Ca2+ go after it diffuses out of the sarcoplasmic reticulum?

A

It attaches to the troponin on the actin myofilaments.

83
Q

Rigor mortis

A

The short-term stiffening that occurs after death.

84
Q

Why does rigor mortis set in after death?

A

For Ca2+ to be gathered into the sarcoplasmic reticulum, active transport must occur, which takes energy. After death, the cells no longer produce ATP so active transport stops, leaking Ca2+ into the muscle fibers and causing cross bridges to form. There is no more ATP, though, so the muscle cannot uncontract.

85
Q

Antagonist muscle

A

A muscle which performs the opposite action of the muscle in question.

86
Q

Motor unit

A

One motor neuron and all the muscle fibers it innervates.

87
Q

What does it mean for a neuron to innervate a cell?

A

It means a branch from the neuron’s axon closely approaches the cell at a synapse.

88
Q

What does a small motor unit look like?

A

One neuron that might branch ten times and innervate ten different muscle fibers.

89
Q

What does a large motor unit look like?

A

One neuron that might branch a thousand times and innervate one thousand muscle fibers.

90
Q

What factor affects how finely an entire muscle is controlled?

A

The amount of branching in a motor unit.

91
Q

What is the all-or-none law of skeletal muscle contraction?

A

An individual muscle fiber contracts maximally in response to an action potential.

92
Q

Why do all of the muscle fibers in a motor unit contract at the same time?

A

A motor neuron produces a single action potential that travels equally to all muscle fibers in its unit. This makes them all contract at the same time because there is only one action potential.

93
Q

Why don’t entire muscles contract in an all-or-none way?

A

Whole muscle can perform in a graded fashion because it is comprised of multiple motor units. An individual motor unit follows the law, but a combination of units can be gradual.

94
Q

What does action potential need to be carried on an axon?

A

The neuron must be stimulated to produce the action potential by a part of the brain. When the stimulus occurs, action potentials can be generated to run down the axon of the neuron.

95
Q

Subthreshold stimulus

A

A stimulus too small to create an action potential in a neuron.

96
Q

What happens when a subthreshold stimulus is applied to a motor neuron?

A

No muscle contraction takes place because no action potentials stimulate the muscle fiber.

97
Q

Threshold stimulus

A

A stimulus strong enough to create one action potential in a neuron.

98
Q

What happens when a threshold stimulus is applied to a neuron?

A

A single action potential is created.

99
Q

Submaximal stimuli

A

Stimuli of increasing strength that create more action potentials along more neurons.

100
Q

What happens when submaximal stimuli are applied to a neuron?

A

Multiple action potentials are created.

101
Q

Maximal stimulus

A

A stimulus that is strong enough to create action potentials on all motor neurons to a particular muscle.

102
Q

What happens when a maximal stimulus is applied to a neuron?

A

An action potential is created in every motor neuron of the muscle.

103
Q

Supramaximal stimulus

A

Stimulus beyond the level of maximal stimulus.

104
Q

What happens if supramaximal stimulus is applied to a neuron?

A

Nothing. All the motor units have already been activated by the maximal stimulus.

105
Q

What does it mean for a motor unit to be recruited?

A

It means the muscle fibers in it have contracted.

106
Q

How does multiple motor unit summation work?

A

The number of motor units recruited determines the force of the muscle contraction. If only a few motor units are recruited, the whole muscle contracts with a small amount of force. If many are recruited, the whole muscle contracts with great force.

107
Q

Muscle tone

A

The state of partial contraction in a muscle, even when the muscle is not being used.

108
Q

Why does muscle tone never disappear entirely?

A

The motor units within a muscle take turns contracting and relaxing so that some motor units are always recruited in the muscle.

109
Q

Atrophy

A

The state of a muscle cell in which it continues to live, but has shrunk due to the disconnection of the cell from the nerve that controls it.

110
Q

What is ATP formed from?

A

Adenosine triphosphate is formed from adenosine diphosphate (ADP) and a phosphate group.

111
Q

What are the three basic ways ATP is generated in a skeletal muscle?

A

Aerobic respiration, anaerobic respiration, or with creatine phosphate.

112
Q

Aerobic respiration

A

A multistep process in which glucose reacts with oxygen, and the energy released from that process is used to drive the reaction of ADP and P into ATP.

113
Q

In aerobic respiration, how many molecules of ATP are produced from one molecule of glucose?

A

36.

114
Q

When is aerobic respiration used?

A

It is used during periods of rest, when energy demands are low, warm-up, and activities such as long-distance running.

115
Q

What are the consequences of aerobic respiration’s dependence on oxygen?

A

The speed with which aerobic respiration can be performed is dependent on the amount of oxygen available. In vigorous exercise, oxygen cannot get to the muscle fibers fast enough.

116
Q

Creatine phosphate

A

A high-energy molecule stored in skeletal muscle.

117
Q

What is the creatine phosphate reaction?

A

Creatine phosphate + ADP = Creatine + ATP

118
Q

Why is creatine phosphate useful for muscle fibers?

A

The muscle can use it as a very fast energy source when aerobic respiration is unavailable.

119
Q

What is the primary downfall to creatine phosphate?

A

A muscle fiber has only enough creatine phosphate to sustain itself for 10 to 15 seconds of vigorous contractions.

120
Q

Anaerobic respiration

A

The first step in aerobic respiration, but can be used on its own in circumstances in which the muscle needs more energy desperately.

121
Q

What is the first step of anaerobic respiration?

A

Glycolysis.

122
Q

Describe the reaction that occurs in glycolysis.

A

A glucose molecule is broken down into two pyruvic acid molecules and generates 4 ATPs. The pyruvic acid molecules are converted into lactic acid which diffuses out of the muscle fibers into the blood.

123
Q

How many ATPs are produced from one glucose molecule in anaerobic respiration?

A

2.

124
Q

Why can lactic acid have negative effects?

A

If too much anaerobic respiration takes place, lactic acid builds up in the muscle fibers and causes damage and fatigue.

125
Q

Oxygen debt

A

The oxygen needed to restore aerobic respiration and a creatine phosphate supply after vigorous exercise and anaerobic respiration.

126
Q

What benefits does warm-up’s increase in muscle temperature bring?

A

It increases all chemical reactions such as production and breakdown of ATP, cross bridge formation and breaking, and the movement of calcium ions out of the sarcoplasmic reticulum.

127
Q

What benefits does warm-up’s benefits in blood flow to the muscle bring?

A

Oxygen, glucose, and other fuel molecules such as fatty acids are delivered much more quickly to the muscle.

128
Q

What benefits does cool-down have?

A

Cool-down maintains the blood flow to the muscle after exercise and washes away the lactic acid from the muscles and into the blood.

Human Biology (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions